Block diagonalization aided precoding algorithm for large MU-MIMO systems

Large Multi-User Multiple-Input Multiple-Output (MU-MIMO) system is considered as a potential technique to serve a high number of users simultaneously increasing the achievable data rates. By large we mean a large number of transmit antennas (Nt) at the base station (BS) and a large number of downlink user's terminals (UTs). In large MU-MIMO systems, the complexity of precoding algorithms becomes a bottleneck. In this work, we propose a low complexity precoder scheme with two steps. In the proposed scheme the UTs are classified into B blocks. Thereby, in the first step, the interference between block users block is mitigated using a Block Diagonalization (BD) method. In the second step, the interference between users belonging to the same block is palliated employing a more complex precoding. Simulation results show that the proposed scheme can achieve suitable performance while offering lower computational complexity than a nonlinear precoding.